Process for the production of precoated metal

ABSTRACT

Process for the production of a precoated metal which comprises laminating a film resin layer on the surface of a metal material through an intermediate layer comprising a radical curable resin and achieving unification of said laminated product by irradiating said laminated product from above with an electron beam having an energy capable of being transmitted to the surface of the metal material.

United States Patent [1 1 Takahashi et al.

[ 1 March 6, 1973 [54] PROCESS FOR THE PRODUCTION OF PRECOATED METAL[75] Inventors: Masao Takahashi; Jiro Mibae; Takamitsu Ino; RyuheiTakigawa; Shuji Fujioka, all of Ohtsu, Japan [73] Assignee: TorayIndustries, Inc., Tokyo, Japan 22' Filed: March 9, 1970 [21] Appl. No.:17,643

[30] Foreign Application Priority Data March 11, 1969 Japan ..44/18027[52] US. Cl. ..l56/272, 161/216, 161/252, 204/l59.l5

[51] Int. Cl. ..B0lj H10 [58] Field of Search ....l56/272; 204/l59.15,159.14; 161/188, 216,252

[56] References Cited UNITED STATES PATENTS 3,261,336 8/1965 Magat et a1..204/159.15 X

RELATIVE DOSE 3,201,336 4/1966 Burlant ..204/159.15 X 3,520,714 7/1970Miller ..204/l59.15 X 3,157,560 1l/1964 Livingston et al........204ll59.15 X 3,437,513 4/1969 Burlant et a1 ....204/159.15 X3,542,587 11/1970 Aronoff et al. ..204/159.l5 X 3,252,880 5/1966 Magatet al..... ..204/l59.15 X 3,081,244 3/1963 Campanile 156/272 3,287,19711/1966 Errede ..156/272 Primary ExaminerCarl D. Quarforth AssistantExaminer-E. E. Lehmann AttorneySherman and Shalloway [5 7] ABSTRACTProcess for the production of a precoated metal which compriseslaminating a film resin layer on the surface of a metal material throughan intermediate layer comprising a radical curable resin and achievingunification of said laminated product by irradiating said laminatedproduct from above with an electron beam having an energy capable ofbeing transmitted to the surface of the metal material.

2 Claims, 2 Drawing Figures DEPTH (mm) PATENTEUHAR 61973 v l'o l'2 f4DEPTH (mm) f2 .3 .4 .5 .6 DENSITY x DEPTH ELECTRON ENERGY g/mz/Mev) m wm @E wmoo NSF/3mm PROCESS FOR THE PRODUCTION OF PRECOATED METAL Thisinvention relates to a pronoucedly improved process for the productionof a precoated metal possessing excellent properties.

In recent years the production of the precoated metals tends to beincreased to a great degree. This is because the precoated metal as amaterial coated or covered at a stage prior to processing renderscapable of a substantially rationalized process for the manufacture ofmetal wares as compared with the conventional process of coating afterprocessing such as press work. The precoated metals concurrently have aneffectiveness for preventing from tarnishing the metal plate in storageand during the time of transportation.

For such a process for the manufacture of the precoated metal it is amost customary method that a paint is coated on the surface treatedmetal plate by some suitable means, followed by heating at elevatedtemperatures and drying whereby during it.

There are other methods available such that a thin film is caused to beadhered to at the elevated temperatures or adhered in layers through anadhesive agent layer.

Since the precoated metals are mainly used outside the house includingroofing materials and side panels of the house, weather-proofcharacteristics and anti-corrosive property are required of theprecoated metals. To meet this situation the so-called two coats hasbeen recently developed, i.e., the precoated metal is coated twice withpaints with a view of causing the undercoating to contribute for givingan intimate adhesive property with respect of the metal andanti-corrosive property and the top coating for giving processabilityand weather-proof property. However, satisfactory results have not asyet been achieved.

An object of the present invention is to provide a novel process for theproduction of a new precoated metal capable of having excellentcharacteristics over the precoated metals available on the marketconcerning various properties (weather-proofness, anti-corrosiveness,processability, etc.) necessary for a precoated metal, the said processis substantially rationalized as compared with the hitherto process ofthe manufacture.

Other objects of the present invention will be evident from thebelow-mentioned description.

It has been found out that these objects of the present invention can beachieved by laminating in layers a film resin layer on the surface of ametal material through an intermediate layer comprising a radicalcurable resin, the said laminated material being irradiated from aboveit by the electron beam having an energy for transmitting onto thesurface of the metal material.

In the present invention, for metal materials consisting of asubstrative material there are used various types of iron sheets (forexample, untreated bare sheet steel, zinc steel sheet, zinc phosphatetreated sheet steel, metal plates in the form of a thin sheet such asaluminium sheet, copper sheet and metal materials in a variety of formssuch as a rod, wire and mass.

Flat surface is a surface, widely used for forming a laminatedconstruction and other various forms including curved surface and wavyshaped surface may also be used. Further, it is possible to cause aresin layer andpaint film layer to exist on the surfaces of these metalmaterials within the range of the objects of the present invention. Thisis a thin paint film known as service coat, anti-rust paint, etc. and isconsidered en bloc with respect of the metal material.

For materials forming the intermediate layer, i.e., radical curableresins, there are named (l) a vinyl polymer containing unsaturatedgroups at its side chains, (2) an unsaturated polyester prepared byusing as one of starting materials an unsaturated monocarboxylic acid orunsaturated dicarboxylic acid, (3) an unsaturated polyester ether (anepoxy ester) prepared by the condensation of an unsaturated carboxylicacid and an epoxy resin, (4) a melamine polymer containing anunsaturated group (for example, a condensation product of hydroxy alkylmethacrylic acid ester and melamine), (5) an unsaturated polyamideprepared by using as one of starting materials an unsaturatedmonocarboxylic acid or unsaturated dicarboxylic acid and (6) a mixtureof each of the said unsaturated polymers and vinyl monomers. The amountof the unsaturated groups contained in these unsaturated polymers variesin a considerably wide range depend ing upon the properties required ofthe precoated metal. However, in general, favorable results are obtainedin the case of 0.1 to 5, especailly 0.2 to 1.5, mole equivalent per1,000 of the molecular weight of a polymer. The preferred blend ratio ofthe unsaturated polymer and the vinyl monomer is 330-100 by weightpercent to -0 by weight percent.

A mixture of vinyl monomers and a polyurethane prepared by using as astarting material an acid, alcohol, polyether or polyester containing anunsaturated groups can also be used in this invention as a radicalcurable resin forming the intermediate layer.

Moreover, in this invention, a mixture of a saturated polymer andunsaturated monomers such for example as a mixture, say, the so-calledacrylic sirup, of a methyl methacrylate polymer and methyl methacrylatemonomer can be used as the radical curable resin.

For vinyl monomers to be used in the present invention there are namedacrylic acid; acrylates such as methyl acrylate, ethyl acrylate, butylacrylate, cyclohexyl acrylate, octyl acrylate and hydroxyethyl acrylate;methacrylic acid; methacrylates such as methyl methacrylate, ethylmethacrylate, butyl methacrylate and hydroxyethyl methacrylate; acrylicamide; acrylic amide derivatives such as N,N-dimethyl acrylic amide,N-n-butoxycarbonyl acrylic amide; methacrylic amide; methacrylic amidederivatives such as methacrylic amide, N,N-dimethyl methacrylic amide,No-anisyl methacrylic amide; vinyl esters such as vinyl acetate,vinyl-p-chlorobenzoate, and vinyl pelargonate; itaconic acid; itaconicacid esters such as diethyl itaconate; maleic acid; maleic acid esterssuch as diethyl malate; allyl esters such as allyl stearate andmethallyl laurate; vinyl ketones such as methyl-amethyl vinyl ketone;vinyl ethers such as n-hexyl vinyl ether, stearyl vinyl ether; styrene;styrene deviratives such as p-chlorostyrene, a-methyl styrene; olefinederivatives such as 3-methyl-vinyl cyclohexane and 4- phenyl-l-butene;halogenated ethylene such as 1- chloro- 1 ,Z-dibromo-ethylene;acrylonitrile; methacrylonitrile; silane derivatives such as allyltrichlorosilane and chloro-dimethyl-vinyl silane, etc.

An anti-corrosive pigment can be incorporated in the radical curableresin forming the intermediate layer with a view to givinganti-corrosive property to the metal material. Further, various types ofpigments, fillers, dispersing agents, plasticizers and other additivesused for various purposes can be incorporated for a plurality of objectsincluding coloring and hiding effects. Ratios of these substances in thecomposition vary over a wide range according to the properties necessaryfor the intended final product.

According to the process of the present invention, it is necessary touse the radical curable resin in the absence of a solvent. The presenceof any of solvent is not allowed because of causing the adhesiveproperty to be lowered and preventing the surface from being covereduniformly.

As for the film resin layer to be overlaid on the intermediate layercomprising the radical curable resin, substances in the form of a filmcomprising various types synthetic resins are used. Any type of suchresin can be used so long as it can provide satisfaction for theproperties required in accordance with the use as a precoated metal.Most preferable are (l) acrylic film prepared by melt extruding from apolymer composition containing at least 50 by weight percent of esteracrylate or ester methacrylate and by applying other means, (2) apolyester film obtained by for example melt extruding a polyesterprepared from starting materials of a polyethylene terepthalate or apolyester comprising of terephthalic acid and ethylene glycol for themain components. (3) a vinyl chloride resin film prepared by meltextruding from a vinyl chloride resin consisting predominantly of vinylchloride and by applying other means, (4) a fluoropolymer resin filmprepared by melt extruding from a vinylidene fluoride resin consistingpredominantly of a vinylidene fluoride and by applying other means andso forth. No any specific restrictions are made with respect of meansfor forming the films as far as these films of the present inventionpossess a property sufficient enough to meet the request of theprecoated metal.

In order for these films to form a surface layer of a laminatedconstruction and to give a variety of properties (weather-proofness,surface hardness, anti-corrosiveness, processability, decorativeness,etc), as the case may be, various types of pigments, fillers, dispersingagents, plasticizers and other additives for a plurality of purposes areincorporated.

In the present invention, specifically excellent results can be broughtforth in the case of using a resin forming the surface layer and a resinforming the intermediate layer, each containing the same monomerconstituent. For example, if a polyester film is used for the surfacelayer when an unsaturated polyester type resin is used as theintermediate layer, a good result can be achieved.

As for the method for forming a laminated structure, there are variousmethods available and no specific restrictions are imposed thereon. Forexample, it is possible to conduct in such a manner that on the surfaceof the substrative metal material, the radical curable solventless resinlayer is formed by the customary film forming means including byspraying, blushing, melt-coating, electrodeposition process, etc. and byother various means, followed by laminating a film as the surface layerthereon. It is also possible to conduct in such a manner for examplethat the radical curable non-solvent resin layer is formed at the backface of the film forming the surface layer and thereafter, laid inlayers with the metal material.

According to the process of the present invention, by irradiating theelectron beam on the thus obtained laminated construction from above thefilm, the radical curable resin layer is cured and concurently thesubstrative material and the film are intimately adhered to each otherand unified. So far as the electron beam is concerned, there are usedany of the electron beams discharged from various types electron beamaccelerators such as cockcroft type accelerator, cockcroft Walton typeaccelerator, Van de Graff type accelerator, resonant transformer typeaccelerator, insulating core transformer acclerator, linear acceleratortype accelerator, dynamitron type accelerator, high frequency typeaccelerator and the like. Normally, the object of the present inventioncan be achieved by giving a dose of 0. l- 20 Mrad, preferably 0.5-l0Mrad with the electron beam having an acceleration energy of 0.1 to 3MeV.

In the present invention, the total thickness of the film layer and theradical curable resin layer is subjected to the restriction by themaximum transmission distance of the electron beam. For example, in thecase of a material having a density of l g/cm, the maximum transmissiondistance of the electron beam having an energy of 3 MeV'is 13.5 mm andconsequently, the total thickness should not exceed 13.5 mm. Now thatthe density and the maximum transmission distance are in a relation ofinverse proportion, the total thickness will will be made thicker than13.5 mm when the density is less than 1 g/cm.

Each of the attached drawings FIG. 1 and FIG. 2 is a dose-depth curvegraph with a view of giving an explanation of the principle of thepresent invention.

FIG. 1 shows a relation between the depth of a material having a densityof l g/cm in the case of the high energy electron beam passingtherethrough and the absorbed enery imparted by the electron beam.According to this figure it is found out that the absorbed energy on thesurface of the material (depth 0) is only 60 percent of the maximumabsorbedv energy. Namely, in the case of the electron beam having anenergy of 1.0 MeV, for example, the maximum amount of absorption isindicated in the zone of 1.8 mmin depth from the surface and the amountof absorption in the surface zone is about 60 percent of the maximum.

FIG. 2 is a graph showing the generalization of FIG. 1 and it is seentherein that the amount of energy absorption becomes maximum in the zoneof some depth from the surface.

Consequently, in the present invention, the maximum available efficiencyof energy and the improved cure speed can be obtained by using thisprinciple as long as the radical curable resin layer is positioned inthe zone of some depth showing the maximum amount of absorption.

As well known, the radical curable resin is withheld from conducting thecuring reaction by oxygen in the air being a radical inhibitor.According to the process of the present invention, the film-is laid onthe upper layer thereby blocking the air and achieving the effect ofremoving its radical prohibiting work.

Furthermore, in the present invention, in the case where theintermediate layer contains a radical reactive monomer (for examplevinyl monomer such as styrene and methyl methacrylate), these monomerscan be effectively prevented from evaporation.

As for the process for the manufacture of the precoated metal it is thehitherto used method that the laminated construction is formed bycausing acrylic film, vinyl chloride, resin film or fluoropolymer toadhere by heat to the metal material in the condition as they are orthrough the thermoadhesive layer. However, in this case, a single-layerconstruction is formed by means of adhesion of the independent film bypressure at the elevated temperatures and hence, in general, intimateadhesiveness, anti-corrosiveness, process ability are not sufficient.Almost all of the films have a base of thermo-plastic resin formed intoa film by melt extrusion and consequently, the hardness is notsatisfactory.

With view of improving such deficient properties of the film it iscustomarily conducted that the undercoating is generally, made to themetal material thereby imparting it a role for contributing to theintimate adhesion, anticorrosiveness or plural laminated film is made bycovering the film thereby imparting it the same role as abovesaid. Inthe case of giving the undercoating to the metal material, it is usualto dry and cure. it at the elevated temperatures after coating with theundercoating paint. If the drying and curing are not sufficient, theremaining solvents or substances originated from the curing are causedto swell from their escape after the completion of covering the film andit give rise to blister and causes the film to come off. The same thingwill be said in the case of coating the intermediate layer onto thefilm. When the film or metal material is melt-coated with thethermo-plastic intermediate layer, there are no problems as abovedescribed. However, in this case, the intermediate layer is madethermo-plastic whereby not a few deficiencies are seen in such importantproperties as anti-corrosiveness, solvent-resistance property andintimate adhesive property.

On the contrary, according to the present invention, the intermediatelayer is cured by irradating the electron beam to the laminatedconstruction whereby forming a cured resin having the necessaryproperties and concurrently obtaining an adhesiveness between the filmand the substrative material. This is the effect that has never beenbrought forth by the melt-adhesion process. Further, it is anotherpronounced characteristic that by means of the electron beam the filmlayer is cured, for instance, by crosslinking, and in most cases, thedeficient hardness of the film layer consisting of thermo-plastic resincan be improved by crosslinkmg.

The present invention will be explained in particulars by the followingExamples.

EXAMPLE 1 A film of 20p. in thickness was produced by melt extruding at2500 C a composition consisting of 70 parts of a copolymer of methylmethacrylate-ethyl acrylatemethacrylic acid (the weight ratio of70/28/2), parts of titanium oxide white, 7 parts of phthalocyanine blue,7 parts of chrome yellow and 0.2 part of carbon black.

A composition consisting of methyl methacrylateethylacrylate-methacrylic acid(the weight ratio of 40/57/ 3) wasmelt-extruded by 250 C on the surface of the film 1 and covered in thethickness of 5p. thereby producing a composite film with a thickness of25p. (film 11) The below-described composition was coated in thethickness of 5p. on the surface of a zinc phosphate treated sheet steel(0.3 mm thick).

This composition is a liquid composition having a viscosity of 10 poise(3C) consisting of parts by weight of a polymer containing anunsaturated group at its side chain obtained by reacting a copolymer ofethylacrylate-acrylic acid parts/ 15 parts by weight) with 10 parts byweight of glycidyle methacrylate, 30 parts by weight of methylmethacrylate and 25 parts by weight of zinc chromate.

After coating this composition in the thickness of 5;; as abovedescribed, the film (I) was covered thereon and 3 Mrads of 0.5 MeVelectron beam was irradiated from above the film by means of the Van deGraaff type accelerator. The obtained precoated sheet steel wassubjected to the various ASTM tests as shown in Table I.

Further, the film (II) was bonded at 1300C to the surface of the zincphosphate treated sheet steel (0.3 mm thick) with the said covered layerdownwardly whereby a laminated sheet steel was made which was subjectedto various similar tests.

In the case of the precoated metal by means of the electron beam curingmethod, the intermediate layer between the film and the sheet steel isnot only sufficiently cured during a short period of time, but goodphysical properties as shown in Table I are obtained because of anintimate adhesion between them. Further, in this case it is worthattracting a special attention that the obtained hardness is of such asufficient degree that was not obtained by the mere lamination of thethermoplastic acrylic films. It is assumed that this is because theelectron beam irradiation resulted in crosslinking of the upper acrylicfilm. It is evident that by the occurence of such cross-linkages theprecoated metal is concurrently given better resistances to solvent,stains and chemicals.

EXAMPLE 2 A film with a thickness of 25p. was produced by melt extrudingat 280C a composition consisting of 70 parts of polyethyleneterephthalate maleate (terephthalate/maleate 7/3 mol ratio), 23 parts oftitanium oxide white and 7 parts of phthalocyanine blue.

0.3 mol of styrene was mixed with an unsaturated polyester produced from0.5 mol of phthalic acid, 0.3 mol of terephthalic acid, 0.2 mol ofmaleic acid and 1.1 mols of ethylene glycol. 100 parts of thiscomposition was combined with 7 parts of zinc chromate, 20 parts of ironoxide and 3.5 parts of zinc oxide thereby producing a paint.

The above described paint was coated in the thickness of p. on thesurface of the zinc phosphate treated sheet steel and the said polyesterfilm was covered thereon and 4 Mrad of the 0.3 MeV electron beam wasirradiated. This caused the film and the sheet steel to be unifiedwhereby a precoated metal was obtained.

Its properties were such as shown in Table 2.

Table 2 Pencil Hardness 311 Cross hatch-Ericksontape test (6 mm) 100/100180C bend 11 Impact test (1 kg X 50 cm) pass Salt spray test (5% NaClaqueous solution, 500 hrs.) normal EXAMPLE 3 A film with a thickness of20p. was produced by meltextruding a composition consisting of 85 partsof polyvinyl chloride, parts of dioctyl phthalate, 15 parts of titaniumoxide white and 7 parts of phthalocyanine blue.

A polymer having a double bond at its side chain was produced byreacting a copolymer consisting of 0.7 mol of vinyl chloride, 0.2 mol ofethyl acrylate and 0.1 mol of acrylic acid with 0.1 mol of glycidylmethacrylate and a syrup consisting of 70 parts of this polymer, 30parts of methyl methacrylate, 17.5 parts of zinc chromate, 8 parts oftalc and 6.8 parts of zinc oxide was produced.

The said syrup was coated on the zinc phosphate treated sheet steel inthe thickness of 5p. and the said film was covered thereon and by givingit a dose of 4 Mrad radiation of the 0.3 MeV electron beam, a precoatedmetal was produced. The obtained precoated metal achieved good resultsin the adhesive property, weathering property and anti-corrosiveproperty.

The physical properties of the precoated metal are given in Table 3.

Table 3 Pencil hardness F Cross hatch"-tape test 100/100 Crosshatch"-Ericksen (6mm )-tape test 100/100 180 Bend 1T impact test (1 kg X50 cm) pass Salt spray test (500 hrs) excellent Example 4 A zincphosphate treated zinc sheet steel was coated in the thickness of 3;;with an acrylic acid ester as a service coat and cured. Thereafter, thismetalmaterial was coated in the thickness of 5p. with the liquidcomposition of Example 3, followed by covering it with the acrylic filmI of Example 1 and by giving it'a dose of 4 Mrads radiation of 0.5 MeVelectron beam by means of the Van de Graaff, a precoated metal excellentin close adhesive property was obtained.

The physical properties of the precoated metal are shown in Table 4.

Table 4 Pencil hardness H Cross hatch"-tape test 100/ 100 180C bend 1TImpact test (1 kg X 50 cm) pass Salt spray test (500 hrs.) excellentExample 5 An aluminum sheet was coated in the thickness of 5 p. with theliquid composition of Example 3 and then covered with the acrylic filmof Example I, followed by giving it a dose of 4 Mrads radiation of 0.5MeV electron beam by means of the Van de Graaff, whereby-a precoatedcolored aluminum plate excellent in physical properties including theclose adhesive property was obtained.

The physical properties of the precoated plate are given in Table. 5.

Table 5 Pencil hardness 2H Cross hatch"-Ericksentape test (6 mm) 100/100180C bend 0T lmpace test (1 kg X 40 cm) pass Salt spray test (500 hrs.)normal Accelerated weathering (JIS Z0230) weather-O-meter 1000 his.luster retaining ratio: more than Example 6 The following compositionwas coated in the thickness of 5p. on the surface of the zinc phosphatetreated sheet steel (0.3 mm thick).

This composition is a liquid composition having a viscosity of 10 poises(23C) consisting of 70 parts by weight of a polymer containing anunsaturated group at its side chain obtained by reacting parts by weightof a copolymer of methyl methacrylate-butyl acrylateglycidylmethacrylate (the weight ratio of 30/55/15) with 15 parts by weight ofmethacrylic acid, 10 parts by weight of methyl mechacrylate, 20 parts byweight of butyl acrylate and 25 parts by weight of zinc chromate.

After coating this composition as above described, the below-mentionedfilm was covered thereon and 5 Mrads of the 0.5 MeV electron beam wasirradiated by means of the Van de Graaff type accelerator.

The said film is a film with a thickness of 20p. obtained by shaping apolymer containing an unsaturated group at its side chain obtained byreacting 100 parts by weight of a copolymer of methyl methacrylate-butlyacrylate-glycidyl methacrylate (the weight ratio of 30/65/5) with 5parts by weight of methacrylic acid and 50 parts by weight, based onsaid polymer, of titanium oxide.

The physical properties of the obtained precoated sheet steel were shownin Table 6.

Table 6 Pencil hardness l-l Cross hatch-tape test 100/100 Crosshatch"-Ericksentape test (6 mm) 100/100 180C bend T lmlpact test (1 kg X50 cm) pass Sa t spray test NaCl aqueous solution, 500 hrs.) normalAccelerated weathering weather-O-meter (.118 Z 0230) 600 hrs. reductionin luster: 5%

Example 7 The identical liquid composition as in Example 6 was coated inthe thickness of 6 p.on the iron phosphate treated sheet steel (0.18 mmthick) and the belowmentioned film was covered thereon and a dose of 5Mrads radiation of 0.3 MeV electron beam was irradiated.

The said film is a film with a thickness of 20p. obtained in such amanner that a xylene-butanol (the weight ratio of 1/ l solution of a 8:2(weight ratio) mixture of a polymer of methyl methacrylate-ethylacrylate-hydroxyethyl methacrylate-acrylic acid (the weight ratio of30/55/10/5) and hexamethoxymethylated melamine was cast on apolypropylene plate and heated to be cured and thereafter peeled off.

The physical properties of the obtained precoated sheet steel were shownin Table 7.

Table 7 Pencil hardness 21-1 "Cross hatch"-Ericksentape test (6 mm)100/100 180 bend 2T Impact test (1 kg X 40 cm) pass Sa t spray test (5%NaCl aqueous solution, 500 hrs.) normal Example 8 An unsaturatedpolyester was prepared from 0.3 mol of phthalic acid, 0.6 mol ofterephthalic acid, 0.1 mol of maleic acid and 1.1 mols of ethyleneglycol and mixed with 0.1 mol of styrene. A paint was produced bycombining 100 parts of this composition with 6 parts of zinc chromate,25 parts of iron oxide and 3.5 parts of zinc oxide.

On the other hand, a film with a thickness of 20p. was obtained by meltextruding at 280C a composition consisting of 70 parts of polyethyleneterephthalate, 23 parts of titanium oxide white and 7 parts ofphthalocyanine blue.

The said paint was coated in the thickness of 7p. on the zinc phosphatetreated sheet steel and the said polyester film was covered thereon andgave it a dose of 6 Mrads radiation of the 0.3 MeV electron beam wherebya precoated metal integrated with the paint and sheet steel wasobtained.

The physical properties of the precoated metal are given in Table 8.

Table 8 180 bend 1T lmpact test (1 kg X 50 cm) pass Salt spray test (500hrs.) excellent Example 9 A mixture of 20 parts of styrene and parts ofan unsaturated polyester obtained through conducting theheat-condensation of 0.6 mol of phthalic acid, 0.3 mol of maleic acid,0.1 mol of methacrylic acid, 0.7 mol of glycerin and 0.3 mol of ethyleneglycol in the presence of 200 ppm of hydroquinone as a polymerizationinhibitor was coated on the surface of zinc phosphate treated sheetsteel (0.3 mm thick) in the thickness of 10;. The said film was laidthereon and 5 Mrads of 0.5 MeV electron beam was irradiated thereon bymeans of the Van de Graaff type accelerator. The obtained precoatedsheet steel was excellent in adhesive property and in processability.

Table 9 Pencil hardness [-1 Cross hatch-type test /100 180 bend 21Impact test (1 kg X 50 cm) pass Salt spray test (500 hrs.) very goodExample 10 The condensation of 340 parts of trimethylol propane and 300parts of isophthalic acid was conducted by heating to 220C for 2 hours.The obtained polyester was cooled to C and added thereto were 700 partsof partial hydrolyzed substances of phenyl methyl dimethoxysilane, 3parts of isopropyl titanate and 800 parts of cellosolve acetate. Thecondensation was conducted by heating for one hour. A paint was made byadding to the obtained solution 80 parts of TiO per 100 parts of theresin constituent in the said solution and it was coated on the surfaceand heated to be cured thereby obtaining a film.

0.2 mol of styrene was added to a polyester obtained by conducting thecondensation of 0.7 mol of isophthalic acid, 0.3 mol of maleic acid, 0.6mol of trimethylol propane and 0.2 mol of ethylene glycol by heating to130C. to 240C for 5 hours. The resultant solution was coated in thethickness of 10p. on the iron phosphate treated sheet steel and the saidfilm was covered thereon and by giving it a dose of 5 Mrads radiation of0.3 MeV electron beam, an unified precoated metal was obtained. Thismaterial was good both in the adhesiveness of the covered layer andprocessability.

The physical properties of the precoated metal are given in Table 10.

Table 10 Pencil hardness 2H Cross hatch"-tape test 100/100) 180 bend 2Tlririlpact test (1 k X 50 cm) pass S t spray test 00 hus.) excellentExample 1 1 100 parts by weight of finely powdered polyvinyl chloridepolymer a molecular weight of 300,000, 20 parts by weight of dioctyladipate, 50 parts by weight of bis-phenol A-epichlorohydrin type epoxyresin (molecular weightz900, epoxy equivalent: 450), 8 parts by weightof B-napthylamine and 100 parts by weight of TiO were mixed therebyobtaining a composition in the form of paste. This was coated on theTeflon sheet in the form of film and heated thereby obtaining a 45p.thick film.

80 mol percent of vinyl chloride, 10 mol percent of vinyl acetate and 10mol percent of acrylic acid were polymerized in methyl ethyl ketone andthereafter, by adding thereto 10 mol percent of glycidyl methacrylatethe condensation was conducted by heating thereby producing a solutionof a polymer containing an unsaturated bond at its side chain. Thissolution was admixed with 3 percent, based on the resin in saidsolution, of zinc chromate. The resulting solution was coated in thethickness of 10,1. cm the zinc phosphate treated sheet steel and heatedto 50C under reduced pressure thereby removing the methyl ethyl ketone.The said film was covered thereon and irradiated with a dose of 5 Mradsof 0.5 MeV electron beam by means of the Van de Graaff type acceleratorthereby causing the film, intermediate resin layer and sheet steel to beunified and a precoated metal was obtained. The properties of theresultant material were shown in Table 1 l and it exhibited good resultsboth in prooessability and in adhesive preperty.

Table l 1 Pencil hardness H Cross hatch"-tape test 100/100 108 bend 1TSalt spray test No swelling (5% NaCl aqueous solution, normal in all40C, 200 hrs.) other respects Example 12 100 parts of an aqueousdispersion containing 30 percent of a vinylidene fluoride having aparticle diameter of 1 to pand 100 parts of a tricresyl phosphate weremixed and this was spray-coated on the chromium plated plate and treatedby heating to to 180C for a total of 30 minutes. A film with a thicknessof 25p. was obtained.

A copolymer of 0.8 mol of methyl acrylate and 0.2 mol of acrylic acidwas admixed with 0.2 mol of glycidyl methacrylate and the condensationwas conducted by heating thereby producing a polymer containing anunsaturated bond at its side chain.

A composition consisting of parts by weight of this polymer, 20 parts byweight of methyl methacrylate and 50 parts by weight of tricresylphosphate was coated in the thickness of 10g. on the zinc phosphatetreated sheet steel and the said film was covered thereon and given adose of 5 Mrads radiation of 5 Mrads radiation of 0.5 MeV electron beamby means of the Van de Graaff type accelerator. The obtained precoatedmetal exhibited good adhesive properties and passed the 1 kg X 30 cm.impact test by the Du pont type impact testrngrggpirlaztus.

Pencil hardness H Cross hatch"-tape test 100/100 bend 1T lmpact test (1kg X 50 cm) pass Salt spray test (500 hrs.) excellent We claim:

1. A process for the production of a precoated metal which comprisescoating the surface of a metal plate with a radical curable composition,placing a film composed of a synthetic resin in intimate contact withsaid radical curable layer and thereafter irradiating said laminatedproduct with an electron beam having an energy of 0.1 to 3 MeV in a doseof 0.1 to 20 Mrad, said radical curable composition comprising a mixtureof 30 to 100 percent by weight of at least one unsaturated polymerincluding 0.1 to 5 equivalents of carbon-carbon double bonds per 1,000of the molecular weight of said unsaturated polymer and 70 to 0 percentby weight of a vinyl monomer.

2. The process of claim 1 wherein said unsaturated polymer of saidradical curable composition is selected from the group consisting ofvinyl polymers, polyesters, polyester ethers, melamine polymers andpolyamides, and said radical curable composition has a monomerconstituent in common with said synthetic resin.

1. A process for the production of a precoated metal which comprisescoating the surface of a metal plate with a radical curable composition,placing a film composed of a synthetic resin in intimate contact withsaid radical curable layer and thereafter irradiating said laminatedproduct with an electron beam having an energy of 0.1 to 3 MeV in a doseof 0.1 to 20 Mrad, said radical curable composition comprising a mixtureof 30 to 100 percent by weight of at least one unsaturated polymerincluding 0.1 to 5 equivalents of carbon-carbon double bonds per 1,000of the molecular weight of said unsaturated polymer and 70 to 0 percentby weight of a vinyl monomer.